WATER   GAS 
AND  ITS  RESIDUE 


By 

J.  C.  GODBEY,  A.  M. 

•  I 


THESIS 

Presented  to  the  Faculty  of  Vanderbilt 

University  for  the  Degree  of 

Doctor  of  Philosophy 


JUNE,  1910 


TENN. 


CONTENTS 


PAGE 

ACKNOWLEDGEMENT 5 

INTRODUCTION 7 

PART  I.     HISTORICAL 9 

Water  Gas 

Developement  of  the  process  of  Water  Gas 

Making1. 

The  Present  Method  of  making"  Water  Gas. 
The  Composition  of  Water  Gas. 
The  Residue  in  Making  Gas. 
The1* Gas  Oil". 

PART  II.    EXPERIMENTAL 24 

Comparison  of  the  Physical  Properties  of  the  Tar 
and  Oil. 

Distillation  of  the  Tar. 
Distillation  of  the  Oil. 
Effect  of  Light  and  Air  on  the  Fractions. 
Specific  Gravity 
Rate  of  Evaporation. 
Index  of  Refraction. 
Solvents. 

Effect  of  Lowering  the  Temperature. 
Chemical  Analysis  of  the  Tar. 

Distillation  of  the  Tar. 
Analysis  of  the  Distillates. 
The  Residue. 
CONCLUSIONS 48 


V 

V 


ACKNOWLEDGEMENT 


This  work  was  begun  in  the  laboratories  of  Van- 
derbilt  University,  and  was  carried  on  under  the  super- 
vision and  with  the  assistance  of  Dr.  J.  T.  McGill,  to 
whom  I  wish  to  express  my  sincere  gratitude  and  my 
appreciation  of  his  untiring  interest  in  my  work. 


330515 


INTRODUCTION 


The  manufacture  of  water  gas  is  rapidly  becoming 
a  prominent  industry.  As  a  means  of  lighting  and 
heating,  the  gas  has  already  been  accredited  an  equal 
rank  with  coal  gas,  and  bids  fair  to  supplant  it.  The 
present  system  of  carburetting  has  removed  the  dan- 
gers of  poisoning  from  an  odorless  gas,  and  has  also 
produced  a  yellow  flame  suitable  for  lighting  purposes. 
Ix  can  be  cheaply  manufactured  on  a  small  scale  as 
well  as  on  a  large  one.  The  one  serious  drawback,  how- 
ever, is  the  comparatively  useless  residue  which  results 
from  the  process  and  which  is  known  as  water  gas 
tar.  Certain  conditions  in  the  manufacture  of  the  gas 
result  in  a  large  yield  of  tar.  Other  conditions  may 
produce  a  residue  containing  a  high  percentage  of  lamp 
black.  The  density  of  the  tar  seems  to  depend  upon 
the  kind  of  oil  used,  and  the  amount  of  tar  varies  ac- 
cording to  the  length  of  the  "run."  These  complica- 
tions and  the  seeming  relationship  existing  between  the 
oil  used  in  the  run  and  the  residue  have  suggested  a 
comparison  of  the  physical  and  chemical  properties 
of  the  oil  and  the  tar. 

These  investigations  were  begun  in  the  laboratories 
of  Vanderbilt  University  in  May,  1909.  The  material 
was  secured  at  the  plant  of  the  Nashville  Gas  Com- 
pany and  was  taken  from  time  to  time  during  a  space 
of  nine  months.  It  consisted  of  a  number  of  specimens 
of  oil  used  on  different  days  and  the  residue  on  those 
days.  The  portions  used  for  the  comparative  results 
of  the  physical  properties  of  the  oil  and  the  tar  were 
taken  at  the  conclusion  of  a  day's  operating  to  make 

-7  — 


sure  that  the  tar  had  come  from  a  certain  known  oil 
with  which  it  might  be  compared. 

These  precautions  were  taken  because  there  seemed 
to  be  a  difference  in  the  oils  used  at  different  times. 
The  oil  used  at  the  Nashville  plant  is  all  secured  from 
the  Standard  Oil  Company,  and  comes  mostly  from 
Indiana. 

In  the  preparation  of  this  paper  much  information 
has  been  furnishd  by  Mr.  T.  J.  Cunningham,  editor  of 
the  American  Gas  Light  Journal;  Mr.  D.  J.  Collins,  of 
the  United  Gas  Improvement  Company;  Mr.  0.  0. 
Thwing,  chief  engineer  of  the  Western  Gas  Construc- 
tion Company;  Mr.  C.  H.  Houk,  of  the  Standard  Oil 
Company,  and  by  many  others. 

I  wish  to  especially  thank  Mr.  Blake,  Assistant 
Superintendent  of  the  Nashville  Gas  Works,  and  Mr. 
Johnson,  Manager  of  the  Nashville  Chemical  Company, 
for  their  cooperation  and  assistance,  and  for  the  many 
courtesies  extended  by  them  during  these  investiga- 
tions. 


—  8  — 


PART  I— HISTORICAL 

A 
WATER  GAS. 

DEVELOPMENT    OF   THE    PROCESS    OF    MAKING 
WATER  GAS. 

Water  gas  had  its  beginning  in  a  discovery  by 
Cavendish.  In  1784  he  published  his  conclusions  that 
"water  consists  of  dephlogisticated  air  (oxygen)  united 
to  phlogiston  (hydrogen)."1  He  further  demonstrated 
that  water  is  decomposed  by  passing  it  over  redhot 
charcoal.  Since  hydrogen  was  one  of  the  resulting 
gases,  the  product  of  the  decomposition  was  combusti- 
ble. In  the  same  year  Mange,2  Watt,2,  Priestley2  and 
Lavoisier2  had  also  experimented  with  the  decomposi- 
tion of  water  and  had  arrived  at  the  same  conclusions. 

It  was  almost  a  half  century  later,  however,  before 
a  process  for  making  water  gas  was  perfected  and  pat- 
ented. In  1830,  Donovan3  patented  a  process  for  the 
decomposition  of  steam  by  passing  it  over  redhot  coke 
or  charcoal.  The  gas  was  afterwards  enriched  with 
volatalized  oils.  Before  this  time  several  methods  were 
employed  for  passing  steam  into  coal  gas  retorts,  but 

'Phil.  Trans.,  1784,  pp.  13-3  and  137. 

2Life  of  Cavendish — Wilson. 

3Am.  Glas  Lt.  Journ.,  Vol.  XLI.,  p.  209. 

—  9  — 


Donovan's  discovery  is  the  first  process  for  making 
carburetted  water  gas  of  which  we  have  any  mention. 

From  1830  to  1865  was  a  period  of  rapid  develop- 
ment. Many  different  forms  of  apparatus  were  pat- 
ented, and  some  of  the  processes  were  given  practical 
trials.  Those  of  Selligue,1  Jlobard,1  White1  and  le 
Prince1  probably  being  among  the  earliest  of  these. 

The  first  internally  fired  generator  was  patented  by 
George  Lowe2  in  1831.  The  coke  was  heated  redhot  in 
a  retort  and  allowed  to  fall  into  the  generator,  where 
the  heat  was  raised  by  a  natural  draft,  the  top  and 
bottom  doors  being  left  open.  The  doors  were  then 
closed  and  steam  was  admitted  at  the  top.  The  water 
gas  was  taken  off  either  from  the  bottom  or  at  various 
heights  where  the  fire  was  hottest. 

In  1859,  Langlois3  patented  a  process  similar  to  that 
of  Kirkham4  (1852) .  Tubular  retorts  were  used,  being 
heated  by  a  natural  draft  admitted  wherever  the  fuel 
bed  needed  it.  Steam  was  allowed  to  enter  at  the  top 
and  the  resulting  gas  passed  into  a  mixing  chamber, 
where  it  was  carburetted. 

Schaeffer  and  Walcker,5  of  Berlin,  took  out  a  patent 
in  1860  for  "a  new  process  for  the  manufacture  of 
water  gas."  The  process,  in  the  main,  consisted  of 
vertical  retorts  heated  from  below.  The  water,  as 
steam,  was  admitted  at  the  top,  being  decomposed  as  it 


3W.agner's  Jahresbericht,  Vol.  V.,  p.  639. 
2Am.  Gas.  Lt.  Journ.,  Vol.  XLL,  p.  209. 
3Wagner's  Jahreshericht,  Vol.  V.,  p.  639. 

Mahresbericht  der  Chemie,  Vol.  1859,  p.  745;  Annal  de  Chim. 
et  de  Phys.,  Vol.  LI.,  p.  322;  Polyt.  Centralblat,  1859,  p.  119. 
"Journal  fur  Gasbebuchtung,  1862,  p.  63. 

Dingl.  Journal,  Vol.  CLXIIL,  p.  348. 

iPepert.  de  'Chim.  Appl.,  1862,  p.  245. 

Polyt.  Centralblat,  1862,  p.  623,  u.  657. 

—  10  — 


passed  downward.  It  was  then  taken  off  from  below 
and  carburetted  with  oil. 

The  Fages1  process  employed  the  same  kind  of  gen- 
erator as  the  Wilkinson  and  was  known  as  the  "Gaso- 
gene"  process.  It  was  patented  in  1860.  The  appa- 
ratus was  installed  at  Narboune  and  produced  from 
1,000  to  1,200  cubic  meters  of  gas  in  twenty-four  hours. 
Gillard's2  system  was  also  used  at  Narboune,  but  came 
several  years  later. 

In  August,  1863,  W.  H.  Gwynne3  patented  a  process 
to  be  used  in  New  York  City.  The  steam,  which  was 
admitted  at  the  top,  was  superheated  by  passing 
through  pipes  in  the  bench  of  double  retorts.  The  gas 
was  conducted  directly  into  coal  gas  mains.  The  pro- 
cess was  experimented  with  at  Elizabeth,  N.  J. 

W.  H.  Strong,4  in  1877,  took  out  a  patent  for  a 
process  to  be  used  in  Brooklyn,  N.  Y.  The  vertical 
retort  was  used  in  this  system  also,  but  the  steam  was 
admitted  at  the  bottom  and  passed  upward  through 
the  heated  coke. 

November  9,  1881,  P.  Jensen5  patented  a  water  gas 
apparatus  in  London.  It  consisted  of  one  generator 
and  two  regenerators.  These  were  heated  very  hot  by 
the  combustion  of  a  portion  of  the  water  gas  which 
had  been  produced.  While  one  regenerator  was  thus 
heated,  the  steam  was  superheated  in  the  other.  The 
hydrocarbons  were  added  by  means  of  a  shower  of  coal 
dust  automatically  regulated. 

'Genie  Industrielzeit,  1879,  p.  385. 

Polyt.  Centralblat,  1880,  p.  1101. 
2d'Hurcourt,  Deutsche  Industrielzeit,  1868,  p.  254. 
•'Wagner's  Jahresbericht,  Vol.  X.,  p.  697. 
*Patentschrift,  December,  1877. 

Deutsche  Industrielzeit,  1879,  p.  385. 

Industriel  Blotter,  1879,  Vol.  XXVII.,  p.  417. 
•Mourn.  Soc.  Chem.  Ind.,  Vol.  VIII.,  p.  533. 

—  11  — 


J.  B.  Archer1  secured  a  patent  for  a  new  process  on 
May  11, 1886.  Steam  was  superheated  to  1000°  F.  and 
then  passed  through  an  inter jector,  where  it  draws 
with  it  a  quantity  of  oil.  The  steam  and  oil  are  then 
heated  to  2400°  F.,  when  they  are  converted  into  per- 
manent gas.  The  apparatus  is  composed  of  three  con- 
centric, cylindrical  casings  enclosed  in  brick  work  and 
having  the  various  necessary  connections. 

In  April,  1889,  J.  von  Sanger  and  T.  Cooper2  pat- 
ented an  apparatus  with  the  producers  arranged  in 
groups.  These  producers  could  be  operated  with  soft 
coal.  The  arrangement  was  presumed  to  lower  the 
cost  of  water  gas. 

The  Tessie  du  Motay3  process  was  one  of  the  first 
practical  systems.  In  it  was  introduced  the  "up  and 
down  run,"  which  became  a  very  valuable  feature.  The 
steam  was  decomposed  in  the  presence  of  redhot  coke. 
The  "hydrogen,"  as  the  gas  was  incorrectly  called,  was 
stored  in  a  tank  or  holder  from  which  it  was  pumped 
ii-to  an  evaporator,  where  it  was  mixed  with  naphtha 
vapors.  The  water  gas  and  the  vapors  were  then 
"fixed."  The  increase  in  the  cost  of  naphtha  soon 
made  the  gas  too  costly  for  practical  purposes. 

In  1900,  J.  G.  T.  Bormann,4  of  Berlin,  patented  a 
process  in  which  the  combustible  gases  were  produced 
in  a  generator  charged  with  ignited  coke  supplied  with 
air  enriched  with  oxygen.  The  gases  were  conveyed 
through  a  serpentine  pipe  arranged  in  the  brick  work 
of  a  chamber  heated  by  a  furnace.  Steam  was  intro-* 
duced  by  another  similarly  set  pipe,  both  pipes  being 

Mourn.  Soc.  Chem.  Ind.,  Vol.  V.,  p.  471. 
Mourn.  Society  Chem.  Ind.,  Vol.  VIIL,  p.  873. 
3Zeits  Angew.  Chem.,  1894,  pp.  137-142. 
Journ.  iSoc.  Chem.  Ind.,  Vol.  XIX.,  p.  614. 
4Journ.  of  Soc.  of  Chem.  Ind.,  Vol.  XXL,  p.  102. 

—  12  — 


maintained  at  a  temperature  over  1200° C.  This 
gas  which  entered  the  chamber  was  mainly  carbon 
monoxide  and  hydrogen,  the  former  acting  with  the 
steam  to  produce  carbon  dioxide  and  hydrogen.  The 
hydrogen  was  drawn  up  into  the  upper  part  of  the 
superheater,  and  then,  together  with  the  carbon  diox- 
ide, was  carried  to  a  second  generator  containing  incan- 
descent fuel,  which  received  the  carbon  dioxide  and 
the  oxygen  of  the  air  through  a  grate  in  the  side  of 
the  generator.  The  carbon  dioxide  was  reduced  to  car- 
bon monoxide  in  this  generator  and  a  gas  composed 
mostly  of  carbon  monoxide  and  hydrogen  was  thus 
formed.  Part  of  the  gas  produced  in  the  first  generator 
was  utilized  to  heat  the  oxygen-producing  apparatus. 

In  1902,  E.  Fleischer1  patented  a  process  for  mak- 
ing "three  quarters  water  gas."  It  had  two  separate 
blasts  which  were  used  in  succession.  The  first  pro- 
duced carbon  dioxide  and  the  second  carbon  monoxide. 
Ordinary  coal  was  used  in  the  generator. 

G.  Horn2  employed  the  vertical  retort,  but  varied  its 
height  according  to  the  kind  of  combustible  used.  It 
could  be  arranged  for  either  finely  powdered  coal  or  a 
spray  of  oil.  Superheated  steam  was  passed  through  a 
side  of  the  decomposing  chamber,  made  of  grating. 
The  process  was  patented  in  May,  1903.  The  chief 
feature  of  the  system  was  the  continued  production  of 
water  gas.  Other  processes  having  this  feature  were 
those  of  F.  Bauke  and  C.  Fuchs8  (1903)  and  H.  Kop- 
pers4  (1901). 


1U.  ,S.  Pat.  701,556. 

Mourn,  of  Soc.  Chem.  Ind.,  Vol.  XXV.,  p.  1212. 

8Pr.  Pat.,  329,028. 

«Eng.  Pat.,  13,047. 

—  13- 


In  May,  1903,  L.  Guenot1  patented  an  apparatus 
v/hich  automatically  regulated  the  change  from  "make" 
to  "blast"  by  the  rise  and  fall  of  the  gas  holder.  At  the 
lower  end  of  the  producer  were  two  inlet  pipes  and  at 
the  top  one  outlet  pipe  leading  to  a  flue.  These  three 
pipes  were  connected  by  water-sealed  bells  attached  to 
a  lever.  The  rise  and  fall  of  this  lever  regulate  the 
valves. 

The  chief  feature  of  the  Thurman2  process  (1904) 
is  the  way  in  which  the  generators  are  connected — in 
pairs  during  the  "blast"  and  in  series  during  the 
"make."  If  carburetted  gas  is  to  be  made  the  inlet 
valve  for  the  hydrocarbons  is  also  connected  to  the  air 
valve.  The  air  and  water  gas  which  remain  in  the  bot- 
tom of  the  generator  and  the  ash  pit  are  expelled  with 
steam  at  the  end  of  each  phase. 

The  process  almost  exclusively  used  at  the  present 
time  is  the  T.  S.  C.  Lowe3  process.  He  first  perfected 
the  vertical,  internally-fired  generator  with  the  direct- 
ly-connected carburetter  and  superheater  and  the  hy- 
draulic seal.  He  began  his  experimenting  as  early  as 
1875,  and  is  still  continuing  it.  The  Nashville  plant 
employs  the  Lowe  system,  which  will  be  described  fully 
under  "The  Present  Method  of  Making  Water  Gas." 

Opposition4  was  very  bitter  against  water  gas  be- 
fore 1885.  It  was  even  legislated  against  in  some 
States  and  cities.  But  the  present  methods  of  car- 
buretting  and  of  mixing  the  gas  in  coal  gas  mains  has 

JUnder  Internat.  Com.,  May  14,  1903. 
2Fr.  Pat.,  342,578. 

Journ.  Soc.  Chem.  Ind.,  Vol.  XXIII.,  p.  930. 
3Wagner's  Jahresbericht,  Vol.  XXV.,  p.  1204. 

Journ.  Soc.  Chem.  Ind.,  Vol.  XIX.,  p.  614. 
Mourn.  Soc.  Chem.  Ind.,  Vol.  XIX.,  p.  614. 

Science,  Vol.  V.,  p.  303. 


gradually  overcome  this  opposition.  In  the  year  1909 
80%'  of  the  gas  used  in  the  United  States  was  water 
gas. 

THE  PRESENT   METHOD  OF  MAKING  WATER  GAS. 

The  apparatus  used  in  the  manufacture  of  water 
gas  are  divided  into  two  classes ;  first,  those  that  pro- 
duce the  blue  water  gas  only,  which  is  used  just  as 
produced  or  carburetted  separately ;  second,  those  that 
produce  carburetted  gas  directly.  The  plant  on  Four- 
teenth Street,  New  York  City,  is  an  example  of  the 
former;  the  one  at  Nashville,  Tennessee,  employs  the 
latter.  The  blue  water  gas  system  produces  no  residue. 
We  will,  therefore,  confine  the  description  to  the  car- 
buretted water  gas  apparatus. 

For  convenience  it  may  be  divided  into  six  parts: 
(1)  The  Gnerator,  (2)  Carburetter,  (3)  Superheater, 
(4)  Hydraulic  Seal,  (5)  Scrubber,  and  (6)  Condenser. 
Figure  I  is  an  illustration  representing  these  divisions 
and  also  showing  the  many  minor  parts,  such  as  fans, 
sprays,  drains  and  connections. 

The  Generator. — The  purpose  of  the  generator  is  to 
produce  the  pure  water  gas  which  burns  with  a  non- 
Liminous  flame,  or  a  faintly  bluish  one,  and  possesses 
no  odor.  The  pure  gas  is  simply  hydrogen  and  carbon 
monoxide  theoretically  in  equal  proportions.  The  gen- 
erator is  a  cylindrical  steel  shell  of  varying  size  and 
lined  with  a  double  layer  of  fire  brick,  and  having  a 
grate  to  support  the  fuel  which  is  poured  in  at  the 
top.  In  the  side  and  near  the  bottom  are  doors  for 
removing  ashes  and  to  serve  as  manholes  when  repairs 
are  needed.  The  generator  is  filled  with  coke  to  a 

'Sci.  Am.,  Vol.  LXLVIL,  p.  263. 

-15- 


depth  of  seven  to  ten  feet.  This  is  fired  to  an  incan- 
descent heat.  Steam  is  then  sprayed  upon  the  carbon, 
which  has  a  great  affinity  for  oxygen,  hence  H2  is  lib- 
erated from  the  HteO  and  C  and  0  combine  to  form 
CO  and  €02.  The  amount  of  the  C02  depends  upon 
the  degree  of  heat,  depth  of  fuel,  and  amount  of  H2O 
admitted.  The  per  cent  must  be  kept  low  since  the 
presence  of  the  inert  002  lowers  th  candle  power  and 
reduces  the  calorific  value  of  the  gas.  It  is  generally 
estimated  that  every  per  cent  of  €02  reduces  the  power 
one  candle. 

There  are  three  reactions  that  take  place: 

2H20+C=C02-f2H2. 

H20+C=€0+H2. 
C02+C=CO+CO. 

It  was  demonstrated  by  Dr.  Bunte,1  of  Germany, 
that  the  reaction  producing  002  takes  place  from  600° 
— 700°  C2,  and  that  it  is  only  at  a  temperature  of 
1000°  C  that  CO  is  formed.  Hence  the  spray  of  steam 
roust  be  of  short  duration,  because  it  tends  to  lower  the 
temperature  of  the  coke  in  the  generator  and  produce 

C02. 

To  restore  the  high  temperature  a  blast  of  air  is 
forced  through  the  coke  by  means  of  a  fan  run  at  a 
regular  speed.  The  oxygen  of  the  air  unites  to  form, 
first,  C02,  then  CO  as  it  comes  in  contact  with  the 
upper  layer  of  coke.  And  the  proportion  of  C02  again 
depends  upon  the  amount  of  air  admitted  in  the  "blow," 
depth  of  fuel  and  temperature.  There  is  always  more 
CO  during  the  latter  part  of  the  "blow."  It  is  also 
essential  that  the  steam  be  very  dry  so  that  no  water 

lSci.  Am.,  Vol.  LXLVII.,  p.  263. 

-See  also  Journal  of  the  Chem.  Soc.,  Vol.  XLVIII.,  p.  1636. 

-16- 


is  sprayed  upon  the  coke  to  cool  it.  A  trap  for  freeing 
the  steam  from  water  is  generally  employed  and  the 
pipes  are  well  wrapped  with  asbestos. 

The  Carburetter. — In  shape  and  size  the  carbu- 
retter is  very  much  like  the  generator.  It  is  filled  with 
firebrick  arranged  in  checker  work.  The  gas  passes 
from  the  generator  into  the  carburetter  and  the  heat 
of  the  "blow"  is  utilized  to  raise  the  temperature  of 
the  bricks.  When  the  temperature  is  thus  raised  a 
spray  of  oil  is  admitted  and,  being  vaporized,  mixes 
with  the  water  gas  to  enrich  it. 

The  Superheater. — The  superheater  is  very  much 
like  the  carburetter  and  is  a  continuation  of  the  "fix- 
ing'* process.  At  its  top  is  the  stack  valve,  which  is 
opened  during  the  "blow."  The  superheater  is  heated 
by  the  same  process  and  at  the  same  time  as  the  car- 
buretter. 

The  Seal. — From  the  fixing  chamber  the  gas  passes 
into  the  seal.  This  is  a  tank  of  water  kept  hot  by  a 
continuous  flow  from  the  boiler.  The  gas  bubbles 
through  the  hot  water  which  serves  to  cool  out  some 
of  the  residue  which  settles  to  the  bottom.  The  gas  is 
somewhat  cooled,  also. 

The  Scrubber. — As  the  gas  bubbles  through  the  seal 
it  passes  into  the  scrubber.  This  is  a  cylindrical  tank 
filled  with  wooden  trays  kept  moist  by  a  spray  of 
water.  Here  the  greater  part  of  the  tar-like  residue  is 
"scrubbed"  out  of  the  gas  by  contact  with  the  trays. 
It  settles  to  the  bottom  of  the  scrubber  and  is  carried 
off  by  drains. 

The  Condenser. — The  last  process  before  purifica- 
tion, through  which  the  gas  passes,  is  the  condenser. 
In  it  the  gas  comes  in  contact  with  rows  of  water-cooleej 


pipes  which  free  it  from  any  remaining  tar  and  cool 
it  for  the  relief  holder.  In  the  condenser,  and  also 
in  the  "washer,"  it  loses  still  more  of  the  tar  and  heavy 
oil  residue.  The  last  cleaning  process  is  to  free  the 
gas  from  EteS  by  passing  it  through  a  tank  of  iron 
oxide  and  sawdust.  Finally  it  is  carried  to  the  relief 
holder  and  ready  for  distribution. 

THE  COMPOSITION  OF  WATER  GAS. 

Water  gas  varies  in  composition  according  to  the 
process  of  manufacturing.  Some  times  the  gas  is 
made  and  subsequently  carburetted  as  in  the  Dellwick- 
Fleischer  process1  (1896).  Usually,  however,  the  car- 
buretting  is  carried  on  as  the  gas  is  made.  The  follow- 
ing analyses  show  the  composition  of  the  gas: 

1.  The   Dellwick-Fleischer,   Uncarburetted.2 

Carbon  dioxide   4.65 

Heavy  hydrcarbons .05 

Oxygen     20 

Carbon  monoxide   39.65 

Marsh  gas 82 

Hydrogen    50.80 

•Nitrogen    3.83 

2.  The  Carburetted.3 

•Carbon  dioxide   3.4 

Illuminants   12.3 

Oxygen    5 

Carbon   monoxide    29.1 

Hydrogen    30.3 

Marsh   gas    21.3 

Nitrogen .3.1 


'Am.  Gas.  Lt.  Journ.,  Vol.  XCI.,  p.  222. 
Wagner's  Jahresbericht,  Vol.  XLIII. 
2Sci.  Am.,  Sup.  Vol.  LJL,  p.  21706. 
3Cci.  Am.,  Vol.  LXXXIV.,  pp.  39  and  102. 

-18- 


3.  The   Carburetted.1 

Hydrocarbon  vapors    1.2 

Carbon  dioxide    3. 

Heavy  hydrocarbons   12.6 

Oxygen     4 

Carbon    monoxide    28.0 

Hydrogen    31.4 

Methane     20.2 

Nitrogen    3.2 

THE  RESIDUE  IN  MAKING  WATER  GAS. 

The  residue  is  called  tar  because  of  its  resemblance 
tc  coal  tar.  It  is,  however,  of  a  much  lower  specific 
gravity  and  a  much  less  viscosity,  besides  many  other 
differences. 

In  the  process  of  gas-making  the  tar  is  given  off  at 
four  places.  First,  that  which  cools  out  in  the  hydrau- 
lic seal;  second,  the  portion  that  condenses  in  the 
scrubber ;  third,  the  part  that  collects  in  the  condenser, 
and,  fourth,  that  which  cools  out  in  the  "purifier."  In 
each  case  the  cooling  is  carried  on  by  means  of  a  flow  of 
water.  A  steady  stream  of  water  passes  through  the 
seal  and  hence  there  is  much  water  in  this  residue; 
the  scrubber  is  constantly  washed  with  a  spray  of 
water  which  mixes  with  the  condensed  tar.  The  pres- 
ence of  this  large  quantity  of  water  is  one  of  the  chief 
sources  of  difficulty  in  trying  to  utilize  the  residue  or  in 
attempting  to  work  with  it. 

There  is  very  little  difference  in  these  various  resi- 
dues when  the  process  is  correctly  operated.  That 
which  condenses  out  of  the  seal  often  contains  more  or 
less  of  the  gas  oil  which  has  gone  through  the  process 
un cracked.  Various  means  are  used  to  detect  the  oil. 
The  greatest  percentage  of  tar  comes  out  in  the  scrub- 

'Jnternat,  Library  of  Tech.,  Vol.  XX.,  Sec,  52,  p.  2, 

-19- 


ber.  It  collects  on  the  wooden  trays  some  times  in 
such  quantities  as  to  impede  the  process  of  gas-making. 
As  it  cools  it  runs  down  into  a  receiver,  where  it  is  col- 
lected at  the  bottom  of  a  tank  from  which  the  cooling 
v/ater  of  the  scrubber  constantly  overflows.  Being 
heavier  than  the  water,  the  tar  sinks  to  the  bottom. 
Specimens  from  this  tank  were  used  in  the  experi- 
mental part  of  this  research. 

The  tar  from  the  condenser  is  the  same  as  that  from 
the  scrubber.  Some  little  residue  cools  out  in  the  puri- 
fying process,  but  this  is  contaminated  with  the  iron 
and  sawdust. 

The  character  of  the  residue  may  depend  largely 
upon  two  things:  First,  the  kind  of  oil  used  in  the 
"run";  second,  the  way  in  which  the  process  of  gas- 
making  is  regulated.  If  the  "run"  is  long  and  the 
"blow"  short,  the  quantity  of  tar  will  be  large  and  of 
a  lower  specific  gravity.  It  will  contain  more  heavy 
hydrocarbons  and  more  of  the  original  oil.  If  the 
"run"  is  short  and  the  blow  long,  the  tar  will  be  less 
in  quantity,  of  a  higher  specific  gravity  and  a  greater 
viscosity.  More  free  carbon  in  the  form  of  lampblack 
will  be  present  and  the  quality  of  the  tar  will  be  much 
inferior.  The  gas  will  also  be  less  in  quantity  and 
poorer  in  quality. 

The  greatest  of  care  must  be  exercised  in  deter- 
mining the  length  of  time  of  the  "run."  In  some  plants 
a  specially  constructed  pyrometer  is  used  to  keep  the 
temperature  constant  and  uniform.  But  more  often 
the  operator  depends  upon  his  ability  to  judge  of  the 
temperature  with  the  eye. 

As  yet  very  little  use  has  been  found  for  the  tar. 
It  is  usually  pumped  into  a  tank  above  the  furnace  and 

-20- 


used  to  spray  the  coke  with  which  the  furnace  is  fed. 
It  burns  with  a  heavy  smoky  flame. 

THE  "GAS  OIL." 

The  oil  used  to  enrich  water  gas  is  a  product  of 
petroleum.  It  is  almost  universaly  furnished  by  the 
Standard  Oil  Company,  and  consists  of  the  residue 
which  remains  after  the  illuminating  oils  have  been 
distilled  off.  It  is  a  very  dark,  heavy  oil,  with  the 
odor  of  lubricating  oil.  It  is  supposed  to  come  off 
above  250 °C,  but  the  incomplete  process  of  distillation 
leaves  some  of  the  lower  boiling  fractions. 

Crude  petroleum  contains  almost  all  of  the  paraffin 
series  as  follows: 


Gases 
Methane 

Formula 
C      H4 

C 
75.00 

H 

25.00 

Boiling  Point 

Sp.  Gr. 
.559 

Ethane  

.C2     H6.. 

.80.00.  . 

.  .20.00.  . 

.  .  .     .5516 

Propane 

€3    H8 

81.81 

18-19 

—  20°  C 

1.522 

Butane  

.  C4    Hio. 

.82.80.  . 

..17.20.  . 

1°C  

.  .  .   .6(0°C 

Liquids 
Pentane 

C5     Hi2 

83.33 

16.67 

37°C 

.628 

Hexane 

C6    Hi4 

83.72. 

16.28   . 

69°C  . 

.664 

Septane  

.07     Hi6. 

.84.00.  . 

.  .16.00.  . 

.  .       97.5°C.... 

.  .  .     .699 

Octane  
Nonane  
Decane  
Undecane  .  .  . 
Dodecane.  .  .  . 

.08    Hi8. 
.C9    H20. 

.ClO   H22. 

.Cn  H24. 
.Ci2  H26. 

.84.21.  . 
.84.38.. 
84.51.  . 
.84.61.. 
.54.70.  . 

.  .15.79.  . 
..15.62.. 
.  .15.49.  . 
.  .15.39.  . 
.  .15.30.  . 

.  .     125°C  
.  .     136°C  .  . 
.  .     158°C  
.  .     182°C  
.  .     198°C  

...     .703 
...    .741 
...    .757 
...     .765 
.  .  .    .776 

Tridecane 

Ci3  H28 

84.78 

15.22 

216°C 

.792 

Tetradecane 

Ci4  H3O 

84.85 

15.15 

238°  C 

.812 

Pentad  e  cane. 

CIS    £[32 

84.90 

15.10 

258°  C 

.825 

Hexadecane 

Ci6  H34 

84.94 

15.06. 

.     180°C 

.828 

Solids 
Paramyricyl  . 
Paracryl  

.  027  Hs6. 
.630  H62. 

.85.26.. 
.85.31.. 

..14.74.. 
.  .14.68.  . 

'.  '     370°C  .... 

It  will  be  seen  from  a  study  of  this  table  that  the 
gas  oil  would  consist  chiefly  of  those  compounds  above 
Decane   (CioH22),  which  are  either  liquids  or  solids 
'Internal.  Library  of  Tech.,  Vol.  XX.,  Sec.  52. 

—  21  — 


with  high  boiling  points.  The  gas  oil  varies  in  specific 
gravity  from  .770  to  .859,  this  corresponds  to  the  spe- 
cific gravity  of  the  compounds  of  the  Marsh  gas  series 
above  Decane.  The  imperfect  distillation  precludes  a 
complete  separation,  however,  hence  the  presence  of 
some  of  the  series  blow  250°  C. 

The  products  of  crude  petroleum  used  commer- 
cially are : 

'Product.  Boiling  Point 

Natural  gas    Gas 

Rhigolene    0°C 

Gasoline  50°,  70°,  98°,  110°C 

Kerosene    150°,   300°C 

Lubricating   Oil    Above    300°C 

Vaseline    Solid 

Paraffine   Solid 

The  substances  known  to  commerce  which  are  con- 
tained in  gas  oil  would  be  kerosene,  lubricating  oil, 
vaseline  and  paraffine. 

The  amount  of  oil  used  at  a  "run"  varies  according 
to  the  length  of  both  the  "run"  and  the  "blow."  At  the 
Nashville  Gas  Company's  plant  about  thirty-two  gal- 
lons is  used  each  time.  The  oil  is  sprayed  into  the 
carburetter  after  having  been  heated  by  passing 
through  pipes  incased  in  steam  jackets.  The  tempera- 
ture being  very  high  in  the  carburetters,  the  oil  is  at 
once  "cracked."  After  this  instantaneous  vaporization 
it  passes  on  through  the  various  phases  of  the  process. 

The  table  on  the  adjoining  page  is  a  facsimile  of  a 
daily  report  at  the  gas  works  and  is  printed  by  the 
permission  of  the  Nashville  Gas  Company.  It  shows 
the  time  consumed  in  the  "run"  and  in  the  blow,"  the 
amount  of  oil  used  each  time,  the  frequency  with 
which  the  generator  is  fired  with  coke.  Thirty-eight 
pounds  of  coke  and  four  gallons  of  oil  are  used  to  pro- 

—  22  — 


duce  1,000  feet  of  gas.  A  daily  run  will  produce  400,- 
000  feet  of  gas  and  750  gallons  of  tar.  The  tar  varies, 
however,  from  twelve  to  fifteen  barrels. 

This  report  would  show  better  results  if  the  plant 
were  running  steadily  every  day.  According  to  the 
present  system  it  is  operated  only  when  the  supply  of 
coal  gas  is  getting  short  and  a  quick  replenishing  of 
the  holder  is  needed. 


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—  23  — 


PART  II— EXPERIMENTAL 

COMPARISON  OF  THE  PHYSICAL  PROPERTIES 
OF  THE  TAR  AND  OIL. 

DISTILLATION    OF   THE   TAR. 

One  of  the  hindrances  attendant  upon  the  analysis 
cr  utilization  of  water  gas  tar  is  the  very  great  diffi- 
culty with  which  it  is  distilled.  The  excessive  amount 
of  water  always  present  must  be  gotten  rid  of  to  pre- 
vent serious  frothing  or  "bumping"  which  causes  the 
undistilled  liquid  to  be  carried  into  the  delivery  tube. 
Probably  the  best  way  to  remove  the  water  is  to  allow 
the  tar  to  stand  some  time  until  the  greater  part  has 
separated  from  the  water  which  can  be  decanted.  The 
tar  used  in  the  following  tests  was  allowed  to  remain 
thirty  days.  When  the  supernatant  liquid  had  been 
decanted  the  tar  was  shaken  up  with  calcium  chloride 
and  put  aside  for  forty-eight  hours. 

The  flask  used  in  the  distillation  of  the  tar,  and  also 
the  oil,  was  a  600  cc.  round  bottomed  distilling  flask 
v/ith  the  delivery  tube  near  the  top  of  the  neck.  The 
flask  is  preferable  to  the  retort,  because  of  a  better 
f  »*actionation  of  the  low  boiling  portion  of  the  tar. 

The  best  burner  for  heating  is  a  Bunsen  flat  burner 
which  can  be  easily  raised  or  lowered.  This  furnishes 
uniform  heat  over  the  bottom  of  the  flask  and  can  be 
regulated  to  heat  gently  or  to  a  very  high  degree. 

The  flask  was  enclosed  in  an  asbestos  jacket  and 

—  24- 


rested  upon  a  wire  gauze  coated  with  asbestos  paste 
except  a  hole  of  two  inches  in  the  center.  This  pre- 
vented the  radiated  heat  from  affecting  the  thermom- 
eter. 

The  thermometer  was  placed  with  the  bulb  just 
below  the  side  delivery.  The  upper  portion  was  en- 
cased in  a  glass  jacket  to  prevent  any  draft  from  affect- 
ing it. 

Six  tractions  of  both  the  oil  and  the  tar  were  taken 
a?  follows: 

1.  Up  to  160°C.  4.  260°  to  310°<C. 

2.  160°  to  200°C.  5.  310°  to  340°<C. 

3.  200°  to  260°C.  6.  340°  to  360°C. 

Repeated  separations  at  various  temperatures  seem- 
ed to  indicate  these  as  logical  points  for  the  fraction- 
ating. 

An  effort  was  made  to  complete  each  fraction  as 
nearly  as  possible.  The  flame  was  so  regulated  that 
the  distillate  came  over  at  the  rate  of  1-2  drop  a 
second.  When  nearing  the  completion  of  a  fraction 
the  drops  were  diminished  to  one  every  ten  seconds, 
and  finally  ceased  altogether.  The  temperature  having 
fallen  several  degrees,  was  then  gradually  raised  to 
the  original.  This  was  done  several  times  with  each 
fraction. 

DISTILLATION   OF  THE  OIL. 

The  same  precautions  were  observed  in  distilling 
the  oil  as  were  taken  with  the  tar.  Exactly  the  same 
Conditions  were  maintained  in  each  case  and  the  frac- 
tions of  the  one  made  to  correspond  to  those  of  the 
other.  The  oil  distilled  very  quietly  and  rapidly. 

—  25- 


The  tables  given  below  show  the  results  of  these 
distillations : 

The  tar,  125.5  grams. 

Fraction                Range  in  Temp.  Amt.  in  Grams     Percentage 

1.  Up    to    160°'C  5.76                    4,60 

2.  160°     200°C  3.46                     7.36 

3.  200°     260°C  29.38                  30.73 

4.  260°     310°C  29.32                   50.94 

5.  310°    340°C  12.19                  60.67 

6.  340°     360°C  14.04                   71.88 

7.  Residue    35.10                  28.12 

Total    125.25                100.00 

The  oil,  125.5  grams. 

Fraction                Range  in  Temp.  Amt.  in  Grams     Percentage 

1.  Up   to    160°C  1.68                    1.35 

2.  160°     200°C  2.64                    3.46 

3.  200°    260'°C  17.56                  17.49 

4.  260°     310°C  31.29                   42.48 

5.  310°    340°<C  26.25                  63.40 

6.  340°     360°C  15.96                  76.15 

7.  Residue    29.77                 23.85 

Total    125.15                100.00 

The  graph  on  the  adjoining  page  shows  a  com- 
parison of  the  curves  which  these  fractions  may  be 
made  to  represent,  the  tar  by  the  broken  line  and  the 
oil  by  the  solid  one. 

EFFECT  OF   LIGHT  AND  AIR  ON   THE   FRACTIONS. 


All  of  the  fractions  of  the  tar  change  in  color  upon 
long  standing;  the  higher  boiling  ones  becoming  very 
dark.  Two  sets  were  placed  under  the  same  conditions, 
the  one  being  hermetically  sealed  and  as  free  from  air 
as  possible,  the  other  loosely  stoppered.  Very  little 
change  took  place  in  the  distillates  hermetically  sealed 
while  the  other  darkened.  Two  sets  were  again  taken 

—  26  — 


700° 


and  the  one  placed  in  the  light  and  the  other  in  a  very 
dark  place,  both  sets  being  loosely  stoppered.  They 
became  equally  dark  upon  standing. 

Some  of  the  distillates  were  hermetically  sealed 
with  only  a  small  quantity  of  the  distillate  in  a  large 
bottle,  the  air  having  been  left  in  the  bottle.  These 
darkened  also.  We  are  thus  led  to  conclude  that  the 
coloration  is  due  to  oxidation  from  the  air  and  not  to 
a  change  in  the  structure  brought  about  by  the  action 
of  light. 

SPECIFIC  GRAVITY. 

The  specific  gravity  of  the  tar  after  it  had  been 
dehydrated  was  found  to  be  1.0429  at  21.6°  C.  The 
specific  gravity  of  the  oil  was  .8590  at  21.6°  C.,  water 
at  21.6°  being  taken  as  a  standard. 

RATES   OF   EVAPORATION. 

In  order  that  a  comparison  of  the  rate  of  evapora- 
tion might  be  made,  specimens  of  the  tar  and  the  oil 
were  placed  in  open  beakers  on  a  sand  bath  at  88°  C. 
and  allowed  to  evaporate  for  six  hours.  The  oil  lost 
6.05%  and  the  tar  18.47%  by  weight  at  the  end  of  that 
time.  The  tar  has  increased  in  specific  gravity  .042, 
while  the  increase  of  that  of  the  oil  was  very  slight. 
The  loss  in  weight  of  the  tar  seemed  to  be  due  to  the 
elimination  of  water  held  in  suspension,  moisture  hav- 
ing been  collected  on  a  watch  glass  held  above  the 
beaker. 

INDEX  OF  REFRACTION. 

The  Abbey  method  was  used  for  taking  the  index  of 
refraction  of  the  tar  and  the  oil  and  also  their  fractions. 

—  27  — 


The  following  tables  show  a  comparison  of  these  re- 
sults : 

Fraction  Range  in  Temp.    Index  of  Refraction  at  19.5°C 

1.  Up    to     160°IC  1.51J37  1.4333 

2.160°     200°C  1.5109  1.4374 

3.  200°     260°C  1.5636  1.4613 

4.  260°     310°C  1.5837  1.4781 

5.  310°     340°C  1.6215  1.4837 

6.  340°     360°C  1.65158  1.4918 

Original   "Gas   Oil"    1.4809 

Dehydrated   tar    1.6693 

Fraction  Range  in  Temp.      Index  of  Refraction  at  40°C 

1.  Up    to    160°C  1.5037  1.4242 

2.  160°     200°C  1.5097  1.4291 

3.  200°     260°'C  1.5549  1.4537 

4.  260° 310°C  1.5759  1.4613 

5.  310°     340°C  1.6141  1.4769 

6.  340°    360°C  1.6477  1.4849 

Original   Gas    Oil    1.4887 

Dehydrated   tar    1.6761 

SOLVENTS. 

The  following  solvents  were  used  in  which  to  test 
the  solubility  of  the  fractions  of  the  tar  and  the  oil: 
Carbon  bisulphide,  carbon  tetrachloride,  benzol,  cumi- 
nol,  acetone,  petroleum,  ether,  paraffin  oil,  acetic  acid 
and  water.  1  g.  was  dissolved  in  1  cc.  of  the  solvent. 
The  various  results  are  shown  in  the  table. 


—  28  — 


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3              O 

^J 

•g 

^ 

^3 

2 

0 

<« 

h— 

1    I 

1 

1 

c3 

'o 

OB 

1 

i 

3 

»o 

6 

IH 

_e 

SOLVENT 

Water 
trb.  bisulphi 

arb.  tetrach: 
ride. 

Benzine 

Acetone 

Cuminol 

troleum  UJtl 

Parafine  OI 

*o 

o 
53 

tt 
O 

O 

£ 

The  various  solutions  were  stoppered  and  set  aside 
for  thirty-six  hours.  The  carbon  bisulphide  in  which 
the  oil  had  been  dissolved  became  brownish  to  a  slight 
degree,  while  the  tar  solution  had  become  black.  When 
filtered  the  filtrate  came  through  black. 

The  carbon  tetrachloride-oil  solution  had  also  deep- 
ened in  color,  and  the  tar  solution  had  become  black, 
filtering  black  also. 

The  benzine  in  which  the  oil  had  been  dissolved 
changed  from  a  clear  solution  to  a  brown ;  that  in  which 
the  tar  was  dissolved  became  a  deep  black  with  a 
reddish  hue.  It  filtered  black. 

The  cuminol-oil  solution  also  changed  from  a  clear 
to  a  brown. 

The  tendency  of  all  the  solutions  of  both  the  oil  and 
the  tar  was  to  darken  upon  standing.  The  tar,  how- 
ever, showed  a  more  decided  tendency  to  deepen  in 
color.  All  of  the  tar  solutions  are  a  deep  red  or  reddish 
black,  while  most  of  the  oil  solutions  are  either  clear 
or  only  slightly  brown. 

Upon  filtering  the  tar  solutions  the  filtrate  remains 
a  very  deep  color,  showing  that  the  coloration  is  not 
due  to  particles  of  carbon  held  in  suspension.  This 
conclusion  is  verified  by  the  deepening  of  the  color 
upon  long  standing  rather  than  a  settling  out  of  the 
carbon  as  a  precipitate  should  it  have  been  held  in 
suspension. 

EFFECT    OF    LOWERING    THE    TEMPERATURE. 

An  apparatus  for  surrounding  the  tar  or  the  oil 
with  ice  and  salt  was  prepared  (see  Fig.  Ill)  as  fol- 
lows: An  inverted  bottle  (a)  having  the  bottom  cut 
off  was  used  as  the  outer  jacket;  a  long,  parallel- walled 

—  30- 


-A- 


funnel  (b)  was  inserted  through  the  stopper;  the  lower 
end  was  connected  with  an  aspirator;  (c)  over  the 
end  of  the  funnel  was  placed  a  filtering  cloth;  (d) 
when  the  temperature  of  the  liquid  had  been  lowered 
a  gentle  pressure  was  exerted  by  means  of  the  aspirator 
pump. 

The  temperature  thus  obtained  was  not  sufficiently 
low  to  cause  a  distinct  separation  of  solids  from  either 
the  tar  or  the  oil.  At  0°  C.  the  tar  was  unaffected,  but 
the  oil  had  become  viscid.  At  -4°  C.  the  tar  was  still 
unaffected,  while  the  oil  had  congealed  to  a  semi-fluid 
mass.  At  -12°  C.  the  tar  showed  a  slight  change.  The 
oil,  however,  had  frozen  solid  and  would  not  spill  from 
an  inverted  vessel.  A  slight  pressure  was  then  exerted 
by  means  of  the  aspirator  and  an  unsolidified  liquid 
was  forced  out.  A  comparative  test  of  this  liquid  and 
the  frozen  portion  in  the  funnel  showed  no  difference 
in  specific  gravity  nor  index  of  refraction. 

The  various  distillates  of  the  tar  and  oil  were  then 
placed  in  a  mixture  of  salt  and  ice  at  -8°  C.  All  of  the 
fractions  of  the  tar  remained  unaffected.  I.,  II.,  III. 
and  IV.  of  the  oil  were  also  unaffected,  but  the  higher 
boiling  fractions,  V.  and  VI.,  froze  solid. 

CHEMICAL  ANALYSIS  OF  THE  TAR. 

ANALYSES  ON  RECORD. 

Lieberman  and  Burg1  passed  the  heavy  oils  of  petro- 
leum through  iron  tubes  heated  redhot  and  obtained 
hydrocarbons  of  the  aromatic  series.  They  also  at- 
tempted to  show  a  similarity  between  these  hydrocar- 
bons and  coal  tar.  Experimenting  along  the  same  lines 


'Berichte  der  deut.  Chem.  Gesel,  1878,  p.  273, 

-31- 


Salzman  and  Wichelhaus2  later  came  to  the  same  con- 
clusion. 

L.  Premier3  treated  paraffin  residues  and  certain 
fractions  of  petroleum  coming  off  at  a  very  high  tem- 
perature with  -bromine  and  found  that  these  high  boil- 
ing products  readily  absorbed  bromine  and  contained 
aromatic  hydrocarbons. 

Matthews  and  Gouldon,4  in  an  analysis  of  the  tar 
from  water  gas  carburetted  with  Russian  oil,  obtained 
the  following  results: 

Benzine    1.19% 

Toluene    3.83% 

Light    Paraffine     8.51% 

Solvent  -Naphtha 17.96% 

'Phenols    Trace 

Middle   Oils    29.14% 

Creosote    Oils    24.26% 

•Napthalene    1.28% 

Anthracene    (crude)    0.93% 

Coke    9.80% 


Total     96.90'% 

In  1882,  Dr.  A.  H.  Elliott1  began  an  analysis  of 
v-ater  gas  tar  from  gas  carburetted  with  naphtha.  He 
found  a  large  percentage  of  naphthalene  and  2.63%  of 
anthracene,  but  mentions  no  other  constituents.  The 
following  table  shows  the  result  of  his  distilation: 

Temperature  .  Weight  of  Distillate 
degrees  Celsius  from  100  Volumes 
80-200  9.2  1-3  Oil 

2-3  Solid 
200-270     11.2  Solid 

17.7  Oil 
270,    Pitch     6.0  Solid 

26,5  Oil 

Last   Fraction    1.7  Semi-solid 

6.0  Oil 
Total  ..78.3 


'Am.  Chem.  Journ.,  Vol.  VI.,  p.  248. 
2Berichte  der  deut.  Chem.  Gesel,  1878,  p.  431. 
3Am.  Chem.  Phys.,  Vol.  XVIL,  p.  5. 
Journ.  Chem.  Soc.,  Vol.  XXXVL,  p.  1025. 
4Gas  World,  Vol.  XVI.,  p.  625. 

-32- 


The  naphtha  used  to  enrich  the  gas  from  which  the 
comes  in  the  above  analysis  is  that  fraction  of 
petroleum  which  comes  over  below  150°  C.  In  the 
present  system  of  carburetting  the  oil  used  is  the  frac- 
tion above  250°  C.  It  is  that  portion  of  crude  petro- 
leum which  remains  directly  after  the  illuminating  oil 
distillate  has  been  taken.  This  oil  is  known  to  com- 
merce as  gas  oil,  and  is  used  at  the  Nashville  Gas 
Works. 

DISTILLATION   OF  THE  TAR. 

In  order  that  larger  quantities  of  the  various  frac- 
tions of  the  tar  might  be  obtained  for  experimental 
purposes,  a  number  of  distilations  were  conducted  at 
the  works  of  the  Nashville  Chemical  Company.  A 
f  ourteen-gallon  still  was  provided  and  so  arranged  that 
the  flames  could  heat  the  sides  and  bottom  uniformly. 
A  hole  was  bored  in  the  top,  in  which  was  inserted  a 
glass  tube  sealed  at  the  lower  end.  In  this  tube  the 
thermometer  was  placed.  The  still  was  also  provided 
with  a  condenser  and  a  long  delivery  tube. 

In  the  final  distillation,  the  fractions  of  which  will 
be  referred  to  in  this  discussion,  the  following  fractions 
were  taken: 

I.  Up  to  160°C.  V.  265°-295°. 

II.  160°-210°.  VI.  295°-335°. 

III.  210°-245°.  VII.  335°-365°. 

IV.  245°-265°.  VIII.  365°   solid. 

Water  was  found  to  be  present  in  fractions  I.  and 
II.,  but  only  traces  above  that,  the  total  percentage  be- 
ing between  8.6%  and  9%.  In  former  distillations 
v,  Ith  inferior  material  as  much  as  19.3%  to  20%  of 
water  was  found  to  be  present  and  came  over  with 
almost  every  fraction. 

-33- 


The  water  was  always  decanted  before  the  tar  was 
placed  in  the  still,  but  some  of  it  was  held  in  suspen- 
sion. This  was  liberated  only  upon  heating  strongly. 
Douglas1  succeeded  in  dehydrating  the  tar  by  heating 
it  in  a  closed  boiler  under  ten  atmospheres  pressure, 
leaving  only  1%  of  moisture. 

27.27  liters  of  the  tar  were  placed  in  the  still  and 
the  heating  was  carried  on  very  slowly  at  first.  The 
flow  from  the  delivery  was  kept  uniform.  Toward  the 
last  the  water  in  the  condenser  was  drawn  off  so  that 
the  higher  boiling  oils  would  come  over  freely.  The 
total  time  consumed  in  the  distillation  was  nine  hours. 

The  following  table  gives  the  results  of  the  distilla- 
tion on  the  larger  scale: 

Range  in  Specific  Amt.  in  Cubic 

Fraction              Temp.  Gravity  Centimeters  Percentage 

Water   1.0020  2350                8,62 

1.  Up    to    160°C  .8854  1900                 6.61 

2.160°     210°C  .9219  2350                 8.62 

3.  210°     245°C 

4.  245°     265°C  .9624  2600 

5.  265°     295°C  .9795  2500 

6.295°     335°'C  .9940  3650 

7    335°     365°C  1.0342  3700 

Residue    5850 


Total    25900  90.95 

ANALSIS  OF  THE  DISTILLATES. 

The  Water. 

The  water  which  came  over  in  fractions  I.  and  II. 
was  separated  from  the  tar  distillate  by  means  of  a 
separatory  funnel.  When  thoroughly  freed  from  tar 

Mournal  of  Gas  Lighting,  1891,  p.  1130. 

-34- 


it  had  a  faint  greenish  blue  color,  a  weak  alkaline  reac- 
tion, and  a  specifis  gravity  of  1.0020  at  28°  C.,  water  at 
28°  being  taken  as  the  standard.  A  small  quantity  was 
warmed  with  NaOH  in  a  closed  flask  with  a  small  de- 
livery tube.  An  ammoniacal  odor  was  detected  and  red 
litmus  was  turned  blue.  500  cc.  of  the  water  was  acid- 
ulated with  hydrochloric  acid  and  allowed  to  stand  for 
twenty-four  hours.  At  the  end  of  that  time  a  deep 
blue  precipitate  had  settled  out.  This  was  filtered, 
washed  with  water  containing  a  few  drops  of  hydro- 
chloric acid  and  the  precipitate  dried  at  100°  C.  A 
portion  of  the  precipitate  fulfilled  the  following  test  for 
ferric-ferrocyanide  Fe4(FeCy6>3,  Prussian  blue.  It  is 
soluble  in  concentrated  acids  but  reprecipitated  upon 
dilution;1  soluble  in  ammonium  tartrate;2  soluble  in 
oxalic  acid,  but  entirely  reprecipitated  when  exposed 
for  a  time  to  sunlight.3  When  strongly  heated  it  glows 
and  is  reduced  to  ferric  oxide,  Fe203/  It  is  insoluble 
in  water,  alcohol  and  dilute  acids.5 

These  tests  were  further  confirmed  by  subjecting 
the  brownish  residue  which  remained  after  the  pre- 
cipitate had  been  heated  to  redness,  to  the  following; 
dissolved  in  hydrochloric  acid  and  a  portion  tested  with 
potassium  f errocyanide ;  a  deep  blue  color.  Another 
portion  was  tested  with  potassium-sulpho-cyanide ;  a 
red  color.  A  third  portion  was  made  alkaline  with 
ammonium  hydroxide ;  a  deep  blue  color.  These  prove 
the  base  to  be  iron.  A  portion  of  the  precipitate  was 


1Watt's  Chem.  Die.,  Vol.  II.,  p.  289. 

2Berichte  der  deut.  Chem.  Gesel,  Vol.  VIII.,  p.  1503. 

"Berichte  der  deut.  Chem.  Gesel,  Vol.  III.,  p.  12. 

*Watt's  Chem  Dis,,  Vol.  II.,  p.  289. 

BIbid, 

-35-^ 


subjected  to  Lassaigne's  test1  for  nitrogen,  sulphur  and 
the  Halogens  Nitrogen  was  the  only  one  found  to  be 
present. 

Besides  the  ferric-ferrocyanide  there  may  be 
present  ferrous  ferrocyanide  and  ferrous-ferricyanide, 
since  ferric  salts  oxydise  ferro-  to  ferri-cyanides,  while 
ferrous  salts  reduce  ferri-  to  ferro-cyanides.2 

A  small  amount  of  cyanogen  which  is  probably 
present  in  the  gas  as  hydrocyanic  acid,  acts  upon  the 
oxide  of  iron,  formed  by  the  action  of  the  oxygen  on 
the  sides  of  the  generator  and  carburetter,  to  produce 
iron  cyanides.  This  cools  out  in  the  scrubber  and  hence 
is  found  in  the  tar. 

The  filtrate  was  then  evaporated  to  dryness  and  left 
a  brownish  residue.  A  portion  of  this  was  heated  to 
redness  on  a  platinum  foil.  It  burned  with  no  flame 
and  left  a  brownish  red  residue  which  was  tested  for 
inorganic  substances  and  found  to  be  ferric  oxide, 
Fe2O3,  and  ferric  chloride,  Fe2C16. 
•  In  an  analysis  of  the  gas  from  the  gas  plant  iron 
was  found  to  be  present,3  probably  in  the  form  of  iron 
carbonyl,  FeCO,  or  iron  pentacarbonyl  Fe(CO)5.  Iron 
carbonyl  has  also  been  found  in  water  gas  and  coal  gas 
which  has  been  compressed  in  iron  cylinders.4  The 
existence  of  a  volatile  compound  of  iron  has  been 
known  since  1891,  in  which  year  it  was  discussed  by 
Dr.  F.  Quincke  before  the  British  Chemical  Society.5 
When  iron  is  brought  in  contact  with  hydrogen  gas  and 
then  treated  with  carbon  monoxide  the  issuing  gas 
is  found  to  contain  iron.  When  this  gas  comes  in 

'Carbon  Compounds — Weston,  p.  3. 

^Berichte  der  deut.  Chem.  Gesel,  Vol.  VIII.,  p.  1503. 

3Analysis  of  Dr.  W.  H.  Hollinshead,  1909. 

4Proc.  Chem.  Soc.,  1891,  p.  126. 

5Journ.  Chem.  Soc.,  1891,  Vol.  LIX.,  p.  604. 

-36- 


contact  with  aliphatic  oils  the  iron  compound  is  par- 
tially absorbed,  but  is  decomposed  upon  exposture  to 
the  air,  with  a  separation  of  iron  hydroxide.1  Further- 
more, a  trace  of  iron-tetra-carbonyl,  Fe  €464  has  been 
found  in  mineral  oils.2  Iron  hydroxide  being  soluble 
would  appear  in  the  filtrate  of  the  water  as  an  iron 
chloride. 

A  portion  of  the  residue  from  the  evaporated  filtrate 
was  partly  dissolved  in  absolute  alcohol.  After  stand- 
ing a  few  days  the  alcohol  evaporated,  leaving  a  brown- 
ish colored  residue.  Cubical  crystals  separated  out  of 
a  water  solution  of  this  brownish  residue.  These  when 
burned  gave  off  a  vapor  and  seemed  to  indicate  the 
presence  of  an  organic  base  which  has  not  yet  been 
determined. 

Fraction    I., 160°    sp.    gr.   .8854,   6.61%. 

500  cc.  of  fraction  I.  was  dried  with  calcium  chlo- 
ride and  refractionated,  using  the  hempel  three-bulb 
tube  and  completing  each  fraction  as  in  the  distillations 
on  a  small  scale. 

Fraction  Range  in  Temp.  Amt.  in  C.  'C. 

1.  60°     100°C  65 

2.  100°     120°C  93 

3.  120°     160°'C  184 

Residue  above 160° C  158 

These  fractions  were  again  refractionated,  giving 
the  following  results: 
Fraction  1 : 

Fraction  Range  in  Temp.  Amt.  in  C.  C. 

a.  60°    80°C  2 

b.  80'°    85°C  27.5 

c.  85°     100°C  20 

Above    100°>C  15.5 


Mourn.  Chem.  Soc.,  Vol.  LIX.,  pp.  605  and  1090;   Treatise  on 
Chem.,  Roscoe  and  Schorlmner,  p.  1019. 
Mourn.  'Chem.  Soc.,  Vol.  LIX.,  p.  1093. 

—  37  — 


Fraction  2-1-  residue  from  1. 

a.  85°    100°  C  35 

b.  100°    105°C  10 

c.  105°     115°C  40 

d.  115°    120°C  22 

Above    120°C  1.5 

Fraction  34-  residue  from  2. 

a.  120°  130°C  57.5 

b.  130°  150°'C  83 

c.  150°  160°C  10 

Above  160°C  32 

Fractions  la  and  Ib  were  tested  for  carbon  bisul- 
phide according  to  the  method  devised  by  Nickels.1  A 
portion  of  the  distillate  was  treated  with  a  solution  of 
potassium  hydroxide  in  absolute  alcohol  (1  g.  in  20  cc) 
and  the  mixture  agitated  thoroughly.  But  no  potas- 
sium xanthate,  K2C2H5(CO)S2,  separated  out  nor 
did  the  solution  become  yellow. 

Thiophene,2  641148. 

Fraction  Ib  was  tested  for  thiophenes  by  means  of 
the  indophenin  reaction.3  The  mixture  of  isatin  and 
strong  sulphuric  acid  was  turned  blue,  indicating  a 
trace  of  thiophene.  If  present  in  larger  quantities  the 
color  would  have  been  a  brown.  This  reaction  is  also 
characteristic  of  thiophenic  acid,  C4H3  SCOOH,  or  de- 
rivatives of  thiophene. 

Benzene,  C6H6,  b.  p.  80°-82°. 

Fractions  Ib,  Ic  and  2a  were  treated  with  benzene 
as  follows:4  Thoroughly  agitated  with  concentrated 
sulphuric  acid,  keeping  thoroughly  cooled,  until  fresh 

xChem.  News,  Vol.  XLVIII  (1881),  p.  148,  250. 

Ibid,  Vol.  L  (1885),  p.  170. 
2Berichte  der  deut.  Chem.  Gesel,  Vol.  XVI.,  p.  1465. 

Coal  Tar  and  Ammonia,  Lunge,  p.  190. 
Commercial  Organic  Anal.,  Allen,  Vol.  II.,  ph.  2,  p.  164. 
4Ibid,  Vol.  II.,  part  2,  p.  157. 

—  38  — 


quantities  of  the  acid  are  not  blackened  upon  continued 
shaking.  Wash  with  water  and  sodium  hydrate.  Again 
wash  and  dry  with  calcium  chloride.  Distill  and  collect 
the  portion  which  comes  over  below  90°  separately. 
This  fraction  was  redistilled  and  almost  the  entire  frac- 
tion came  over  at  80°-82°.  The  fractions  were  then 
cooled  to  0°  C.,  and  this  one  froze  solid.  A  few  drops 
of  this  distillate  were  mixed  with  1  cc.  of  nitric  acid 
(sp.  gr.  1.42)  and  1  cc.  of  sulphuric  (sp.  gr.  1.84)  and 
heated  to  boiling  for  thirty  seconds.  The  mixture  was 
poured  into  cold  water,  filtered,  washed  with  alcohol 
and  crystallized  from  alcohol  in  fine,  nearly  white 
needles,  which  melted  at  89.50°,  the  melting  point  of 
dinitro  benzene.1 

When  treated  with  concentrated  H2S04  fraction 
Ib  lost  67%  by  volume,  while  fractions  Ic  and  2a  lost 
nearly  90%.  16  cc.  of  benzene,  m.  p.  80°-82°  was  ob- 
tained from  500  cc.  of  fraction  I.,  being  0.22%  by 
volume  of  the  tar. 

Toluene,  C;H8,  b.  p.  111°. 

Fractions  2a,  2b  and  2c  were  thoroughly  agitated 
with  concentrated  sulphuric  acid  till  fresh  acid  was  no 
longer  darkened,  washed  with  water  and  sodium  hy- 
droxide and  dried  over  calcium  chloride  and  redistilled.2 
The  portion  from  110°-112°  was  collected  separately. 
'Ihe  fractions  were  risdistilled  and  cooled  to  0°  C.,  but 
no  sign  of  congealing  or  crystallization  appeared  after 
standing  twenty-four  hours  at  this  temperature.  Three 
drops  of  the  hydrocarbon  were  mixed  with  1.5  cc.  of 
fuming  nitric  acid  and  1.5  cc.  of  fuming  sulphuric 

^dent.  of  Pure  Organic  Comp.,  Mulliken,  p.  200. 
2Coal  Tar  and  Ammonia,  Lunge,  p.  623. 

—  39  — 


acid.  After  thirty  seconds  the  reaction  mixture  was 
poured  into  cold  water,  filtered,  washed  with  alcohol 
and  recrystallized  from  alcohol  in  nearly  white  needles, 
which  melt  at  70.5°  C.,  which  is  the  melting  point  of 
dinitrotoluene.1 

When  treated  with  concentrated  sulphuric  acid 
fraction  2c  lost  66.3%  by  volume.  2a  and  2b  lost  95%. 
8.8  cc.  of  toluene  was  gotten  from  500  cc.  of  distillate 
1,  or  a  total  of  .11%  of  the  tar  is  toluene. 

Xylene;  CSHio  b.  p.  138°-142°. 

Fraction  3b  was  treated  with  120%  of  concentrated 
sulphuric  acid  and  shaken  up  for  thirty  minutes.  It 
was  then  washed  with  sodium  hydroxide  and  water, 
dried  over  calcium  chloride  and  redistilled.  Para- 
xylene3  being  insoluble  in  cold  concentrated  sulphuric 
acid  is  unattacked  but  the  meta-4  and  ortho-5xylenes 
form  soluble  sulphonates  and  can  be  separated  from 
the  sulphuric  acid  solution.6  Dilute  the  solution  with 
water,  neutralize  with  barium  carbonate,  'filter  off 
the  barium  sulphate,  concentrate  the  filtrate  by  evap- 
oration, and  divide  into  two  parts.  Set  one  portion 
away  and  allow  the  barium  salts  to  crystallize.  Treat 
the  remainder  with  a  slight  excess  of  sodium  carbon- 
ated, and  concentrate  by  evaporation.  After  standing 

^Edent.  of  Pure  Organic  Comp.,  Mulliken,  p.  202. 
2Am.  Chem.  Pharm.,  Vol.  LXIX.,  p.  162. 

Ibid,  Vol.   CLXXXVL,  p.   331. 

Journ.  Prakt.  Pharm.,  Vol.  LXL,  p.  74. 

Ibid,  Vol.  LXX.,  p.  300. 

3Treatise  on  Chem.,  Roscoe  and  Scharlemmer,  Vol.  III.,  part 
4,  p.  388. 

Coal  Tar  and  Ammonia,  Lunge,  p.  156. 

Berichte  der  deut.  Chem.,  Gesel,  Vol.  IX.,  p.  405. 
4Ibid,  Vol.  X.,  p.  1010. 
5Ibid,  Vol.  CLIIL,  p.  265. 
•Treatise  on  Chem.,  Vol.  III.,  part  4,  p.  388. 

—  40  — 


for  several  hours  large  prism  shaped  crystals  of  so- 
dium ortho-xylene  sulphonate1  C6H2  (CH3)2  SOs  Na+ 
5H20,  crystallize  out.  A  portion  of  the  crystals  were 
treated  with  hydrochloric  acid,  nitrated  with  fuming 
nitric  acid  crystallized  from  alcohol  and  the  melting 
point  taken.2 

Since  sodium  meta-xylene  sulphonate  does  not  crys- 
tallize it  was  separated  from  the  filtered  solution  by 
means  of  HC1,  nitrated,  and  the  melting  point  of  the 
nitro  compound  taken. 

The  portion  of  the  xylene  which  did  not  form  a  sul- 
phonate was  washed  with  water  and  sodium  hydrate 
redistilled,  and  a  few  drops  nitrated1  as  follows :  Boiled 
with  1  c.c.  of  fuming  nitric  acid  and  2  c.c.  concen- 
trated sulphuric  acid,  for  1  minute.  Poured  into  cold 
water,  filter,  wash  with  alcohol.  These  crystals  were 
clusters  of  white  needles,  which  were  trinitro  para- 
xyleneC6H  (CH3)2  (N02)3.2 

The  amounts  of  para-  meta-  and  ortho-xylenes  in 
xylene  have  been  variously  estimated.  Usually,  how- 
ever, meta-xylene  has  the  largest  percentage  and  ortho- 
the  smallest.  Levinstein5  has  found  in  various  sam- 
ples of  crude  xylene: 

Paraxylene   3 — 10% 

Metaxylene    70 — 87% 

Orthoxylene    2 — 15% 

Paraffine    3 — 10% 

When  a  mixture  of  the  three  xylenes  is  treated  with 
bromine  containing  1%  of  iodine,  they  are  converted 
into  the  tetra-bromo-xylenes,  C6Br4(CH3)2.  If 

treatise  on  Chem.,  Vol.  III.,  part  4,  p.  388. 

2Ident.  Pure  Org.  Comp.,  Mulliken,  p.  203. 

3Ident.  Pure  Org.  Comp.,  Mulliken,  p.  202. 

4Berichte  der  deut.  Chem.,  Gesel,  Vol.  X.,  1010;  Xi.,  22. 

5Ibid,  Vol.  XVII.,  p.  444. 

—  41  — 


heated  to  160°-170°  this  yields  the  tetra-brom-phthalic 
acids  quantitatively;  C6Br4  (CH3)2-f  6Br2+4H20=C6 
Br4  (C02H)2+12HBr.  Since  these  can  be  readily 
separated,  the  composition  of  the  original  mixture  can 
be  determined  in  this  way.1 

Fraction  3b  when  refractionated  yielded  20  c.c.  be- 
tween 136°-142°.  This  is  4%  of  fraction  I  or  .27% 
of  the  tar.  Of  this  amount  para-xylene  represents 
.05%. 

Cumene,  C6H3(CH3)3. 

An  effort  to  determine  the  presence  of  trimethyl 
benzene  resulted  in  a  sulphonated  product  of  distillate 
3b,  but  since  little  is  known  of  cumene,  no  satisfactory 
qualitative  tests  were  applied.  Cumene  has  been  found 
in  crude  petroleum.2 

Ferric  ferrocyanide  was  found  to  have  come  over 
in  the  low  boiling  fractions  of  distillate  I.  and  sepa- 
rated out  of  the  dilute  sulphuric  acid  solution.  Its  pres- 
ence was  not  detected  above  fraction  3b. 

Fractions  II.  and  III.,  160°-245°,  6.82%  sp.  gr.  .9219. 

500  c.c.  was  refractionated  as  follows : 

Fraction  Range  in  Temp.  Amt.  in  C.  C. 

1.  100°    160°C  67 

2.  160°  200°C  181 

3.  200°  211°C  102 

4.  215°  235°C  95 

5.  235°  245°C  14 

Residue   above    245°C  37 

Refractioning. 

Fraction  1. 

a.  100°    120°C  9 

b.  120°    130°C  16.5 

c.  130°     150  °C  22.5 

d.  150°    16$°'C  10.5 

Above    ,  160  °C  8.5 


'Compt.  rend.,  Vol.  CI.,  p.  1218. 
2Am.  <Chem.  Pharm.,  Vol.  CCXXXIV.,  p.  89. 
Berichte  der  Chem.,  1876,  p.  256. 

—  42- 


Fraction  Ic  was  treated  for  xylene  and  gave  an  addi- 
tion of  5  c.c.  crude  xylene,  making  a  total  of  .32%  in 
the  tar. 

Naphthalene,  CioHS,  m.  p.  81°. 

Fractions  3,  4  and  5  were  cooled  to  4°C  for  24  hours. 
A  white  crystalline  solid  separated  out.  This  was  fil- 
tered while  cold,  the  oil  pressed  out,  purified  with  sul- 
phuric acid  and  manganese  dioxide  and  recrystallized 
from  alcohol.  Its  melting  point  was  found  to  be  78°- 
80°C,  and  its  boiling  point  218°>C.  .1  gram  of  the 
crystals  was  treated  with  picric  acid  and  the  melting 
point  of  the  long  hair  like  needles  separating  out,  was 
found  to  be  150.5°,  which  is  that  of  naphthalene  pic- 
rate,  CioH4C6H4(N03)201.  Fractions  II.  and  III. 
yielded  1.28%  of  naphthalene,  the  greater  part  coming 
over  in  fraction  4,  which  was  almost  entirely  solid. 

Phenol,  C6H50H,  m.  p.  42,  b.  p.  183. 

Fraction  III.  was  agitated  with  sodium  hydroxide, 
filtered,  neutralized  with  sulphuric  acid  and  tested  for 
phenols  with  ferric  chloride.  There  was  no  trace  of  a 
coloration.  Nor  could  any  deep  colored  nitro  com- 
pound be  produced.  The  solution  was  also  unaffected 
by  bromine  water. 

Fraction   IV.,  245°-265°,  9.53%  sp.  gr.  .9624. 

500  c.c.  was  redistilled  and  divided  into  four  frac- 
tions : 

Fraction  Range  in  Temp.  Amt.  in  C.  C. 

1.  200°  215°C  79 

2.  215°  235°C  258 

3.  235°  245°C  54 

4.  245°  260°C  46 

Residue    above  ..260°C  73 


'Ident.  of  Pure  Org.  Comp.,  Mulliken,  p.  200. 

—  43  — 


Fractions  1,  2  and  3  were  cooled  to  4°C,  the  naphtha- 
lene pressed  out  while  cold,  purified  and  crystallized., 
Yield,  1.08%. 

Fraction  V.,  265°-295°,  9.16%,  sp.  gr.  .9795. 

500  c.  c.  was  redistilled  as  in  the  preceding  frao 
tions. 

Fraction  Range  in  Temp.  Amt.  in  C.  C. 

1.  200°  ...................  215°  15 

2.  215°  ...................  235°  160 

3.  235°  ...................  245°  118 

4.  245°  ...................  260°  9:5 

5.  260°  ...................  295°  85 

.79%  of  naphthalene  was  gotten  from  fractions  1,  2 
and  3.  This  makes  a  total  yield  of  naphthalene  from 
fractions  II.,  III.,  IV.  and  V.  of  3.13%. 

Fraction  VI.,  295°-335°,  13.38%,  .9940  sp.  gr. 

A  crystalline  solid  settled  out  of  fraction  VI.,  which 
was  of  a  greenish  fluorescent  color  very  unlike  naph- 
thalene. It  was  thoroughly  shaken  up  and  500  c.c. 
was  redistilled. 

Amt.  in  C.  C. 
10 
25 
20 
93 
148 
27 
47 
26 
14 
90 

A  very  small  amount  of  naphthalene  separated  out 
of  fraction  1. 


F 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 

raction 
200°      

Range  in  Temp. 
215°C 

215°                   .    . 

235°C 

235°     

245°C 

245°          

260°C 

260° 

290°C 

290°     

300°C 

300°                

320°C 

320°     , 

340°C 

340°    

360°C 

Residue    above    . 

360° 

Anthracene,  CuHio,  m.  p.  213°,  b.  p.  351°. 

The  greenish,  fluorescent  solid  appeared  in  fractions 
7,  8  and  9.     These  fractions  were  cooled  in  ice  at  o°C 

—  44  — 


for  24  hours  and  filtered  while  cold.  The  crystals 
were  pressed  out,  freed  from  oil  and  dried  at  100°,  re- 
distilled and  purified  with  NaOH.  .1  gram  was  oxi- 
dized with  chromic  acid  and  the  residue  crystallized 
from  alcohol.  The  melting  point  of  the  compound 
was  found  to  be  279°-280°,  which  is  that  of  anthra- 
quinone.1  To  further  verify  the  test  the  anthraquin- 
o.ae  was  converted  into  oxanthranol.  When  anthra- 
cene is  thus  oxydised  it  yields  anthraquinone.  Yield 
of  anthracene  from  fraction  VI.,  0.26%. 

Fraction   VII.,  235°-265°,   1.0342  sp.   gr.,   13.57%. 

Fraction  VII.  was  treated  as  the  other  distillates. 

Fraction  Range  in  Temp.  Amt.  in  C.  C. 

1.  260°  290°C  100 

2.  290°  300°C  98 

3.  300°  32'0°C  93 

4.  320°  3400lC  60 

5.  340°  360°C  100 

6.  360°  365°€  13 

Residue    above     365°C  36 

Fractions  2,  3,  4  and  5  were  cooled  to  0°C  for  24 
hours  and  filtered  while  cold.  The  anthracene  was 
purified  as  in  VI.  Yield,  .434%,  making  a  total  of 
.694%  of  anthracene  in  the  tar.  The  amount  of  an- 
thracene oil  from  which  it  crystallized  was  27.9%  of 
the  tar. 

Paraffins. 

The  high  boiling  fractions  from  240°-365°  when  sul- 
phonated  left  a  residue  which  was  clear  and  oily.  It 
was  carefully  washed  free  from  sulphuric  acid  and 
the  sulphonates  and  dried  over  calcium  chloride.  The 
index  of  refraction  was  found  to  be  but  slightly  above 
that  of  fraction  VI.  of  the  gas  oil.  The  sulphonation 
was  repeated  and  the  index  of  refraction  lowered 

—  45- 


.0115,  which  made  it  almost  the  same  as  that  of  the 
gas  oil.  In  a  discussion  of  the  sulphonation  test,  Dean 
and  Bateman1  have  this  to  say:  "If  a  fraction  from 
the  distillation  of  creosote  oil  be  treated  under  proper 
conditions  with  concentrated  sulphuric  acid  it  will  be 
converted  into  a  mixture  of  sulphonic  acids,  which  will 
readily  dissolve  in  water.  If,  however,  there  are  par- 
affin bodies  present  they  will  not  be  attacked  to  the 
same  degree  as  the  aromatic  hydrocarbons  and  when 
the  products  of  the  sulphonation  are  treated  with  wa- 
ter the  paraffin  compounds  will  remain  as  residual 
oil."  Applying  this  test  the  tar  seemed  to  show  the 
presence  of  unchanged  aliphatic  compounds  of  gas  oil. 
The  following  gives  the  results  of  the  chemical  anal- 
ysis in  tabulated  form. 

Water    , 6.61% 

Ferric    ferrocyanide    Trace 

Carbon  bisulphide   None 

Thiophene    Trace 

Benzene    22% 

Toluene    11% 

Orthoxylene    

Meta-xylene 

Para-xylene     05% 

Cumene    Trace 

Phenol   None 

Naphthalene   3.13% 

Anthracene   oil    (270°-365°)    27.9  % 

Anthracene     V 65% 

Paraffine    High  % 

Residue    21.45% 

This  analysis  is  not  completed,  since  an  effort  has 
been  made  to  discover  the  presence  of  only  the  more 
common  aromatic  hydrocarbons. 

The  residue  which  remains  after  the  six  fractions  of 
the  tar  have  been  taken  is  a  very  black  tar  which  re- 
sembles "No.  24"  of  coal  tar  distillates.  It  is  more 

"Circular  112,  Forest  Service  Series. 

-46  — 


brittle,  however,  and  has  a  much  less  range  of  elas- 
ticity. It  becomes  very  brashy  at  a  freezing  tempera- 
ture, and  liquifies  at  the  temperature  of  a  warm  sum- 
mer day.  This  would  preclude  its  use  as  a  paving 
material,  unless  mixed  with  coal  tar. 

A  series  of  experiments  were  conducted  under  the 
observation  of  the  author  at  the  Nashville  Chemical 
Company,  with  mixtures  of  coal  tar  and  water  gas 
tar  above  360°.  A  very  good  grade  of  tar  was  pro- 
duced, but  the  tendency  to  separate  out  on  the  part  of 
the  unchanged  paraffn  gave  some  trouble.  A  high 
percentage  of  water  was  also  found  to  be  present,  and 
the  difficulties  of  distillation  were  greater  than  in  coal 
tar.  There  seemed  to  be  present  a  rather  large  quan- 
tity of  free  carbon  in  the  form  of  lamp  black.  This 
lowered  the  utility  of  the  tar  very  greatly.  Neverthe- 
less, the  increasing  manufacture  of  water  gas  and  the 
demand  for  a  substitute  for  coal  tar  made  by  the  pres- 
ent method  may  finally  lead  to  the  commercial  utiliza- 
tion of  water  gas  residue.  When  the  process  of  its 
production  has  been  so  perfected  that  the  residue  is 
always  uniform,  and  the  danger  of  producing  a  high 
percentage  of  lamp  black  has  been  removed,  then  it 
will  become  marketable. 


-47  — 


CONCLUSIONS 


1.  The  gas  oil  used  in  the  process  of  carburetting 
water  gas  undergoes  a  chemical  and  physical  change 
when  converted  into  water  gas  tar. 

2.  Some  of  the  oil  goes  through  the  process  un- 
changed, or  nearly  so,  and  may  be  detected  in  the  dis- 
tillation above  250°C. 

3.  No  phenols  were  found  in  the  fractions  below 
260°C. 

4.  Benzene,  Toluene,  Xylene,  Naphthalene  and  An- 
thracene were  found  in  the  tar. 

5.  The  tar  varies  in  density  and  constituency.    This 
is  governed,  first,  by  the  gas  oil  used  in  the  run;  sec- 
or.-d,  by  the  method  in  which  the  process  of  water  gas 
formation  is  conducted. 

6.  Because  of  a  low  range  of  flexibility  and  elastic- 
ity of  the  pitch  the  tar  is  not  practicable  as  a  substitute 
for  coal  tar  in  the  preparation  of  paving  compounds, 
but  may  be  of  some  utility  when  mixed  with  it. 


—  48- 


RETURN 


C.RCUIAT.ONOEFARTMENT 


LOAN~PERIOD 
HOME  USE 


Gaylord  Bros. 

Makers 

Syracuse,  N.  Y. 
PAT.  JAN.  21,  1908 


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